Seven people were injured when two cargo trains collided on tracks under a Missouri highway overpass, causing the overpass to partially collapse.

Scott County Sheriff’s Dispatcher Clay Slipis said the collision happened around 2:30 a.m. Saturday near Chaffee when a Union Pacific train hit a Burlington Northern train.

Slipis said several cars derailed and hit a pillar of the Highway M overpass, bringing it down. Two cars were on that stretch of road.

Seven people — five in the vehicles and both train conductors — were taken to a hospital. Slipis said all but one was treated and released; the seventh is in good condition.

The National Transportation Safety Board says it’s sent a crew to investigate the cause.